Automatic vehicle transmissions incorporate roller clutch assemblies that act as speed sensors to smooth the shifting process. The roller clutch has an inner race and an annularly spaced outer race, with a complement of caged rollers located therebetween. Often, the outer race is the pathway race, meaning that it has a cylindrical inner surface pathway that the rollers roll on. Two interleaved sets of friction plates surrounding the outer race are alternately pushed together or released to selectively transfer power between the transmission's torque converter and the particular gear set served by the input unit. One of the sets of plates is tied to the outer race, generally by being fitted over axial splines on the outer surface of the outer race. Therefore, a series of gaps is formed by the interleaved plates, arrayed along the length of the outer race. When the roller clutch overruns, the clutch plates are released and rotate very rapidly relative to one another, with a very close clearance. To avoid over heating between the plates, a flow of cooling lubricant must be supplied to the gaps. Such lubricant generally originates from a central shaft surrounded by the inner clutch race, and is fed into the side of the annular space between the races. From there, the lubricant must somehow get to the gaps between the clutch plates, but the outer race occupies the most direct path.
The most common manner of feeding the lubricant between the interleaved plates is to simply drill feed passages radially through the outer race, from its pathway to its outer surface. As the roller clutch overruns and spins rapidly, lubricant in the annular space is flung out against the pathway, and is thereby forced through the feed passages directly into the gaps between the plates. This approach, although straightforward, presents potential problems, since the rollers roll on the pathway. It is desirable that the entry point of each lubricant feed passage be centrally located, so that the ends of the rollers will not click over it. But, since the gaps between the outboard plates are widely axially separated, it is also necessary that the exit points of at least some of the feed passages not be centrally located. The solution has generally been to drill a large number of small diameter feed passages at an angle, which is difficult and expensive. Furthermore, being angled, the passages are longer, and the pressure drop the lubricant flow experiences through them is greater than would be the case for a straight passage.